To safely operate a large-scaled plant system such as a nuclear (atomic) power plant, an operation monitoring system including a proper man-machine interface is necessarily required. A plant is operatively maintained by way of three tasks “monitor”, “judgement”, and “manipulation” by an operator. An operation monitoring system must be equipped with such a man-machine interface capable of smoothly achieving these three tasks by an operator. In the “monitor” task, the statuses of the plant are required to be immediately, or accurately grasped. During the “judgement” task, a judging material, and information to be judged must be quickly referred by an operator. During the “manipulation” task, such a task environment is necessarily required in which an object to be manipulated and a result of the manipulation can be intuitively grasped, and also the manipulation intended by the operator can be quickly and correctly performed.
The man-machine interface of the conventional operation monitoring system will now be summarized with respect to each of the tasks “monitor”, “judgement”, and “manipulation”.
(1). Monitor
Conditions within a plant may be grasped by monitoring both of data derived from various sensors for sensing pressure and temperatures and the like, and video derived from video cameras positioned at various places of the plant. Values from the various sensors are displayed on a graphic display in various ways. Also, a trend graph and a bar graph are widely utilized. On the other hand, the video derived from the video camera may be displayed on an exclusively used monitor separately provided with the graphic display. More than 40 sets of cameras are installed in a plant, which is not a rare case. While switching the cameras, and controlling the lens and directions of the cameras, an operator monitors various places in the plant. In the normal monitoring task, there is a very rare case that pictures or video derived from the cameras are observed by the operator, and it is an actual case that a utilization factor of the pictures derived from the cameras is low.
(2). Judgement
If an extraordinary case happens to occur in a plant, an operator must immediately and accurately judge what happens to occur in the plant by extensively checking a large amount of information obtained from sensors and cameras. Since the data derived from the various sensors and the pictures or video from the cameras are independently supervised or managed in the present operation monitoring system, it is difficult to refer these data and pictures with giving relationships to them, resulting a heavy taskload on the operator.
(3). Operation
Operations are done by utilizing buttons or levers provided on an operation panel. Recently, there have been proposed such systems that an operation is performed by combining a graphic display with a touch panel, and by selecting menus and figures displayed on a screen. However, the buttons and levers provided on the operation panel, and also the menus and figures displayed on the display correspond to abstract forms irrelevant to actual objects. There is such a difficult case that an operator supposes or imagines the functions of these objects and the results of the operations. In other words, there are such problems that an operator cannot immediately understand which lever is pulled to perform a desired operation, or cannot intuitively grasp which operation command is sent to the appliance within the plant when a certain button is depressed. Also, there is another problem that since the operation panel is separately arranged with the monitor such as the camera, the bulky apparatus should be constructed.
The below-mentioned prior art has been proposed to simplify the camera switching operations and the camera remote control operations with regard to the monitoring task as described in the above item (1):    (a). Graphics produced by simulating an object to be photographed by a camera are displayed on a graphic display. A photographic place or position is instructed on the above-described graphics. In response to this instruction, the camera is remote-controlled so that a desired picture is displayed on a monitor of the camera. This type of plant operation monitoring system is known from, for instance, JP-A-61-73091.    (b). When a process device for performing either an operation, or a monitoring operation is designated by a keyboard, a process flow chart of the designated process device is graphically displayed, and simultaneously a picture of a camera for imaging the above-described process device is displayed on a screen. Such a sort of plant operation monitoring system is described in, for example, JP-A-2-224101.    (c). Based upon a designated position on a monitor screen of a camera for photographing a plant, panning, zooming and focusing operations of the camera are carried out. For instance, when an upper portion of the monitor screen is designated, the camera is panned upwardly, whereas when a lower portion of the monitor screen is designated, the camera is panned downwardly. Such a sort of plant operation monitoring system is described in, for instance, JP-A-62-2267.
On one hand, generally speaking, in a monitoring system such as a process control monitoring system, a method for visually monitoring conditions of the process has been employed by installing a monitor apparatus in a central managing room and an ITV camera (industrial television camera) at the process side and by displaying situations of the process on a monitor by way of a picture taken by this camera. This picture and sound are recorded on a recording medium such as a video tape. In an extraordinary case, the recording medium is rewound to reproduce this picture and sound.
On the other hand, data which have been sequentially sent from the process and are used as a control (control data), for instance, process data (measurement data) are displayed on either a monitor or a meter and the like of the central managing room, are stored in a database within a system, and derived from the database if an analysis is required, or an extraordinary case happens to occur. This conventional system is introduced in the plant operation history display method as opened in JP-A-60-93518.